An imaging apparatus employing a complementary metal-oxide-semiconductor (CMOS) solid-state image sensor has been used in related art as an imaging apparatus such as cameras. This solid-state image sensor has a pixel array portion in which pixels, each of which includes a photoelectric conversion device for generating an electric charge corresponding to incident light, are arranged in a two-dimensional lattice pattern. The alternate execution of exposure in which a charge is generated by the photoelectric conversion device and signal readout in which a signal corresponding to the charge generated by the exposure is read out from the pixel makes it possible to obtain an image signal of one frame. For this solid-state image sensor, a solid-state image sensor including a charge retention region used to retain temporarily the charge generated by the photoelectric conversion device for each pixel is used.
In the solid-state image sensor described above, after the stop of the exposure period, the charges generated by the photoelectric conversion devices in all the pixels are retained in the charge retention region. Then, the charges retained in the charge retention region are transferred to a floating diffusion region in the pixel, and signal reading is performed on the transferred charges. Here, the floating diffusion region is a region to which an amplifier circuit for the signal readout is connected. In this manner, the charges generated in the photoelectric conversion device are retained simultaneously in the charge retention region in all the pixels, so the global shutter function can be achieved. Here, the global shutter is a function to simultaneously start and stop the exposure in all the pixels arranged in the solid-state imaging device. For such a solid-state image sensor, a solid-state image sensor in which a first transfer gate and a second transfer gate are arranged in a charge retention region has been developed. When the charge retained in the charge retention region is transferred to the floating diffusion, the application of a driving voltage and the stop of the application are performed sequentially with respect to the first and second transfer gates. In this manner, a system has been developed in which a potential gradient is generated inside the charge retention region to improve the charge transfer capability (e.g., refer to Patent Literature 1).